Abstract
ABSTRACT Epigenetic reader proteins, such as bromo-domains, are often associated with diseases such as cancer and inflammation. BET bromodomain inhibitors have been studied extensively; however, non-BET bromodomains are understudied. Moreover, available high-throughput biological assays to assess inhibitors are limited. One non-BET bromodomain-containing protein, BPTF, has a recently reported inhibitor, BZ1, with an in vitro affinity of 6.3 nM. Additionally, BZ1 is known to be non-selective towards other class I bromodomains PCAF, GCN5, and CECR2. Here, we use a BZ1 analog, BZ1-THQ, to design a small molecule NanoBRET tracer, MS-1 , for assessing inhibitor functional activity through live-cell target engagement against the BPTF bromodomain. Further, we investigate the versatility of MS-1 against PCAF, GCN5, and CECR2. We observe that MS-1 is a broadly applicable NanoBRET tracer for class I bromodomains, effectively binding BPTF, PCAF, GCN5, and CECR2 in HEK293T cells at low to sub-micromolar concentrations. We report EC 50 values of commercially available and in-house inhibitors to demonstrate tracer versatility for future target engagement studies and inhibitor development. Table of Contents artwork
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ABSTRACT
Epigenetic reader proteins, such as bromo-domains, are often associated with diseases such as cancer and inflammation. BET bromodomain inhibitors have been studied extensively; however, non-BET bromodomains are understudied. Moreover, available high-throughput biological assays to assess inhibitors are limited. One non-BET bromodomain-containing protein, BPTF, has a recently reported inhibitor, BZ1, with an in vitro affinity of 6.3 nM. Additionally, BZ1 is known to be non-selective towards other class I bromodomains PCAF, GCN5, and CECR2. Here, we use a BZ1 analog, BZ1-THQ, to design a small molecule NanoBRET tracer, MS-1, for assessing inhibitor functional activity through live-cell target engagement against the BPTF bromodomain. Further, we investigate the versatility of MS-1 against PCAF, GCN5, and CECR2. We observe that MS-1 is a broadly applicable NanoBRET tracer for class I bromodomains, effectively binding BPTF, PCAF, GCN5, and CECR2 in HEK293T cells at low to sub-micromolar concentrations. We report EC50 values of commercially available and in-house inhibitors to demonstrate tracer versatility for future target engagement studies and inhibitor development.
Competing Interest Statement
The authors have declared no competing interest.
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